The present invention relates to an optical glass lens set and a manufacturing method thereof that relate to assembling of an optical glass lens with a lens holder, especially used in small sized lenses of camera or lenses of mobile phones.
The optical lens module is a basic optical element in cameras or camera phones. In practice, the lens module is formed by at least one optical lens. Refer to FIG. 1, an optical lens 20a is made from optical plastic or optical glass and having an optical surface 21a that generally is a round surface, and an outer periphery 22a around the optical surface 21a that can be round or rectangular. In order to fasten and package the optical lens 20a inside a lens module, firstly locate and fasten the lens 20a in a lens holder 10a to form an optical lens set 1a while the lens holder 10a is made from metal or plastic. Thus the lens 20a is aligned with a central axis (optical axis) of the lens module. Moreover, by an actuator, the lens holder 10a (or the optical lens set 1a) moves inside the lens module so as to achieve zoom in/zoom out, as shown in U.S. Pat. Nos. 7,312,933, 7,095,572 US2007/0024989 and JP3650594. A conventional way of fastening the plastic or glass lens 20a in the lens holder 10a is a shown in FIG. 1, especially suitable for glass lens. At first, design a lens holder 10a according to shape of the outer periphery 22a of the lens 20a such as round or rectangular shape. Then the lens 20a is set into a preset hole for being located. Next use UV glue to fasten the lens 20a, throughout a curing process such as passing a UV curing oven for curing. Due to compact size of the lens 20a, the optical surface 21a is easy to get scratched or attach with the glue (flow) when the lens 20a is located and fastened by automatic or manual gluing, such as Japan patent JP3791615, JP06258562 and U.S. Pat. No. 7,224,542, US2007/0047109. The curing process of the UV curing glue between the glass lens 20a and the plastic lens holder 10a is especially long curing time, difficult operation and lower yield rate. Thus the cost is unable to be reduced.
Recently, a technique that places an insert in a mold cavity and then treated with injection molding is called an insert injection molding method. An insert (metal part) is set into a mold cavity of a preset mold. Then inject melt plastic (or rubber) to fill a preset molding area (material pouring area) and cover whole or part of the insert. After cooling and curing, the product is released from the mold. Such manufacturing method is applied broadly to electric elements, connector, mechanical parts and LED, as disclosed in U.S. Pat. No. 5,923,805, TWM313317, and JP07120610 etc.
While manufacturing a cover with plastic lens by such method, the cover (a housing) is used as an insert and put into a mold cavity. Then a plastic lens is made by plastic injection and is integrated with the cover. Or use the plastic lens as an insert and the cover is made by plastic injection and integrated with the plastic lens so as to form an integrated cover with plastic lens, as shown in TW 0528279 and U.S. Pat. No. 6,825,503. Refer to JP62251113, the window glass plate is used as an insert and is covered by plastic material so as to form a window glass or other parts. Refer to U.S. Pat. No. 6,710,945, by two injection holes for plastic material, a molded lens and a lens holder are molded by injection sequentially. Or use infrared gas as the insert and produce a mount covering the glass by injection molding. Refer to U.S. Pat. No. 7,332,110, in a press molding, the eyeglass frame is used as an insert and is placed into a mold cavity. The preform of the plastic lens is heated to a melt status and then the soft preform is turned into the shape of the cavity by heating and pressing of the mold Thus the preform becomes a lens and integrated with the eyeglass frame to form an eyeglass. However, the press molding technique is unable to be applied to a manufacturing process that integrated the glass lens with the plastic lens holder. Once the plastic lens holder is used as an insert, the softening point of the optical glass is about 500° C. that is far higher than the deformation temperature −80° C. of the plastic lens holder. Thus when the temperature of the mold achieves the softening point of the optical glass, the plastic lens holder has already deformed and unable to be molded. Therefore, the press molding is unable to be applied to mass production of the product that uses a plastic lens holder as an insert and glass as molding material.
Due to requirement of high precision of the optical glass lens set for cameras, the location precision between the glass lens and the lens holder has great effects on imaging of the lens. In order to solve poor yield rate and complicated manufacturing processes caused by glue, there is a need to develop a new technique applied to assembling of the optical glass lens with the lens holder during mass production processes of the high precision optical glass lens set.